In recent years, noble metals are used in a fabrication process with miniaturization and high integration of a semiconductor device. Since contamination of a substrate due to the noble metals adversely affects properties of the semiconductor device, the analysis of the noble metals on the substrate is an important issue.
A method of analyzing substrate contamination due to metals has been used in the related arts in which a metal collection solution scans on the substrate using an automatic collection device, the metals on the substrate are collected into the metal collection solution, and the metals contained in the metal collection solution are analyzed. As the metal collection solution, for example, HF/H2O2, HCl/H2O2, or HF/HCl/H2O2 is used.
However, the above-described analysis method used in the related arts may not be used as a method of analyzing substrate contamination due to the noble metals. This is because the noble metals having high oxidation-reduction potential deprive of electrons of Si constituting the substrate and become metals of noble metals on the substrate, resulting in not being collected by the metal collection solution having relatively weak oxidation power.
Therefore, a method is proposed in which aqua regia or HF/HNO3 having strong oxidation power is employed as a metal collection solution for collecting the noble metals. However, there is a problem that the aqua regia or the like may not scan on the substrate using the automatic collection device, due to low scanning property.
For this reason, when the aqua regia or the like is used as the metal collection solution, it is necessary to apply the metal collection solution onto the wide range or entire of the surface of the substrate by a manual method (by operating engineer). In addition, since the large amounts of metal collection solutions are used, it is necessary to concentrate the metal collection solution after collecting the noble metals. In addition, since the noble metals are collected by the manual method, dedicated instruments or engineers having a high degree of skill acquisition are required.
Thus, according to the analysis method using the metal collection solution of the aqua regia or the like, processes are complicated and it takes a long time for the analysis. Accordingly, it is difficult to efficiently analyze the substrate contamination due to the noble metals in this analysis method. When the substrate has a large diameter in the future, it is increasingly difficult to analyze the substrate contamination using such a method.
For this reason, there is a strong need for a metal collection solution, which can collect noble metals and can scan on a substrate, and a method of efficiently analyzing substrate contamination using such a metal collection solution.